Understanding receiver sensitivity (12db SinAD) in uV mesarement.

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by N8MJS, Aug 12, 2015.

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  1. W6KCS

    W6KCS Ham Member QRZ Page

    I've found this to be true for VHF on mountain tops and urban areas, after years of effective sensitivity measurements all over CA. Not as much for UHF.
     
  2. WB3BEL

    WB3BEL Ham Member QRZ Page

    You need to navigate on the arrl page to the QST archives.

    http://www.arrl.org/arrl-periodicals-archive-search

    Type in the rig you are interested in Title/Keywords box and search to find which issue of QST the review appeared in. Then you can navigate to that and read the report.
     
  3. NJ3X

    NJ3X Ham Member QRZ Page

    Is that a lot?
     
  4. W1VT

    W1VT Ham Member QRZ Page

  5. W6KCS

    W6KCS Ham Member QRZ Page

    It's a lot, but in general there might be a trade-off like better front end filtering with the less-sensitive receiver, or it might be less prone to overloading. Plus, it might not matter if local ambient noise is enough to mask the benefit of the more sensitive receiver.
     
  6. AI3V

    AI3V Ham Member QRZ Page

    It would be the difference on a fm signal from "pretty noisy and not very good copy" to "a bit of noise but not too bad"

    But as noted, the measured difference is 3 db, which would make copy "pretty noisy but I can make you out".

    Note these numbers are on a signal generator, there is enough manmade noise just about everywhere that
    Would "cover up" any difference.

    In use, the big issue is interference from strong transmitters outside the ham band, 99% of the time the real improvement would be a bandpass filter between the rig and antenna.

    When I lived in Pittsburgh I had to add external preselector filters to my 6,144,432 and 1296 mHz rigs.

    Sometimes the interference can be heard as voices or tones, other times,the interference will simply overload the receiver to the point where nothing at all comes out the speaker.

    Rege
     
    W6KCS likes this.

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